Cast Bronze vs. Cast Iron
May 30, 2008 at 12:40 am #10876AnonymousInactive
Carroll in Frederick, Maryland, asks:
When finding a bell for sale, large 28″ or more for a new church, how do you tell the difference between a CAST BRONZE bell to a CAST IRON bell? I’ve read a Cast Bronze Bell has the best sound for a Church. Thanks Carroll
If you can help, please post a response.
This inquiry was originally sent to the ABA’s Internet Coordinator. Responses are opinions of individuals based on their personal research and knowledge.
June 2, 2008 at 1:27 pm #13814hjlongMember
Cast Iron, Steel, Crystal Metal are gray in color and are Ferromagnetic; they will hold a magnet if applied to the surface. Bronze is made of Copper and Tin and is non-ferromagnetic; it will not hold a magnet when applied to the surface. Brass is an alloy of Copper and Zinc and is non-ferromagnetic also. Iron & Steel will rust if not painted; bronze will develop a brown (oxidation) or bluish green (sulfates) patina when exposed to the elements but will not rust. Brass bells will develop a brown or green patina also and may develop pitting due to acid rain causing corrosion of the zinc.
June 4, 2008 at 7:11 pm #13815Carl Scott ZimmermanParticipant
Just a little clarification on the matter of color:
Rust (iron oxide) will usually be a “bright” brown color, but varies somewhat depending on whether it arises from cast iron or steel, and what the additives in the steel are. (Can’t give details of that – inorganic chemistry wasn’t my specialty.)
While statuary bronze may indeed develop a dark brownish patina, bell metal and gun metal (both of which are also forms of bronze) tend to be somewhat different, because the relative proportions of copper and tin are different. (Bell metal approximately 80:20, gun metal approximately 90:10.) Also, because bronze is a mixture, not an alloy, those proportions can vary slightly throughout the casting, and that is highly dependent on the bellfounder’s practices. As a result, if copper predominates at the surface of a bell then a greenish color will result from the oxidation of copper; but if tin predominates then a grayish color will result from the oxidation of tin. It’s quite possible to find a bell which is a mixture of both grayish and greenish patches, though usually the two are intermixed fairly well and yield somewhat gray-green color.
The bluish green color of copper sulphate is much less common on bells except in parts of the country where industrial atmospheric pollutants (e.g., “acid rain”) are a problem.
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